Summary

The coexistence of undernutrition (low birth weight, poor growth) alongside overnutrition (mainly obesity) is a phenomenon afflicting many countries as their economies develop and food availability increases. The focus of the book this phenomenon, otherwise known as the ‘nutrition transition’, which becoming increasingly prevalent in many emerging nations.

Global Changes in Diet and Activity Patterns as Drivers of the Nutrition Transition

Author(s): B.M. Popkin

The nutrition transition relates to broad patterns of diet, activity and body composition that have defined our nutritional status in various stages of history. The world is rapidly shifting from a dietary period in which the higher income countries were dominated by patterns of nutrition-related non-communicable diseases (NR-NCDs; while the lower and middle world were dominated by receding famine) to one in which the world is increasingly being dominated by NR-NCDs. Dietary changes appear to be shifting universally toward a diet dominated by higher intakes of caloric sweeteners, animal source foods, and edible oils. Activity patterns at work, leisure, travel, and in the home are equally shifting rapidly toward reduced energy expenditure. Largescale declines in food prices (e.g., beef prices), increased access to supermarkets, and urbanization of urban and rural areas are key underlying factors.

Regional Case Studies – India

Author(s): K.S. Reddy

As a proportion of all deaths in India, cardiovascular disease (CVD) will be the largest cause of disability and death, by the year 2020. At the present stage of India’s health transition, an estimated 53% of deaths and 44% of disability-adjusted life-years lost are contributed to chronic diseases. India also has the largest number of people with diabetes in the world, with an estimated 19.3 million in 1995 and projected 57.2 million in 2025. The prevalence of hypertension has been reported to range from 20 to 40% in urban adults and 12–17% among rural adults. The number of people with hypertension is expected to increase from 118.2 million in 2000 to 213.5 million in 2025, with nearly equal numbers of men and women. Over the coming decade, until 2015, CVD and diabetes will contribute to a cumulative loss of USD237 billion for the Indian economy. Much of this enormous burden is already evident in urban as well as semi-urban and slum dwellings across India, where increasing lifespan and rapid acquisition of adverse lifestyles related to the demographic transition contribute to the rising prevalence of CVDs and its risk factors such as obesity, hypertension, and type 2 diabetes. The underlying determinants are sociobehavioral factors such as smoking, physical inactivity, improper diet and stress. The changes in diet and physical activity have resulted largely from the epidemiological transition that is underway in most low income countries including India. The main driving forces of these epidemiological shifts are the globalized world, rapid and uneven urbanization, demographic shifts and inter- and intra-country migrations – all of which result in alterations in dietary practices and decreased physical activity. While these changes are global, India has several unique features. The transitions in India are uneven with several states in India still battling the ill effects of undernutrition and infectious diseases, while in other states with better indices of development, chronic diseases including diabetes are emerging as a major area of concern. Regional and urban-rural differences in the occurrence of CVD are the hallmark. All these differences result in a differing prevalence of CVD and its risk factors. Therefore while studying nutrition and physical activity shifts in India, the marked heterogeneity and secular changes in dietary and physical activity practices should be taken into account. This principle should also apply to strategies, policies and nutrition and physical activity guidelines so that they take the regional differences into account.

Regional Case Studies – China

Author(s): S.A. Yin

Over the last 30 years, the nutritional status of Chinese children has greatly improved due to economic development and improved incomes. In this review, the status of childhood malnutrition and obesity in China is evaluated based on the National Nutrition and Health Survey of 2002 (NNHS2002) and the survey on National Student Health and Physical Fitness in China of 2005. Compared with the NNHS1992 survey, the body weights and heights of preschool children in urban and rural areas have significantly improved, and the prevalence of malnutrition (underweight and stunting) has been significantly reduced. However, micronutrient deficiencies, including calcium, zinc, vitamin A, vitamins B1 and B2, are still common in preschool and school children. These data show that the growth and development of Chinese children are under our expectations. On the other hand, the national averaged prevalences of overweight and obesity in the children under 6 years of age are 3.4 or 2.0% as estimated by the Chinese or WHO standards, respectively. We are now facing double challenges: to prevent malnutrition and the increase in overweight and obesity in children.

Regional Case Studies – Africa

Author(s): A.M. Prentice

Africa is the final continent to be affected by the nutrition transition and, as elsewhere, is characterized by the paradoxical coexistence of malnutrition and obesity. Several features of the obesity epidemic in Africa mirror those in other emerging nations: it penetrates the richer nations and urban areas first with a strong urban– rural gradient; initially it affects the wealthy, but later there is a demographic switch as obesity becomes a condition more associated with poverty, and it shares many of the same drivers related to the increasing affordability of highly refined oils and carbohydrates, and a move away from subsistence farm work and towards sedentary lifestyles. Africa also has some characteristics of the obesity epidemic that stand out from other regions such as: (1) excepting some areas of the Pacific, Africa is probably the only region in which obesity (especially among women) is viewed culturally as a positive and desirable trait, leading to major gender differences in obesity rates in many countries; (2) most of Africa has very low rates of obesity in children, and to date African obesity is mostly an adult syndrome; (3) Africans seem genetically prone to higher rates of diabetes and hypertension in association with obesity than Caucasians, but seem to be relatively protected from dislipidemias; (4) the case-specific deaths and disabilities from diabetes and hypertension in Africa are very high due to the paucity of health services and the strain that the ‘double burden’ of disease places on health systems.

Obesity in Emerging Nations: Evolutionary Origins and the Impact of a Rapid Nutrition Transition

Author(s): A.M. Prentice

Here we explore whether there is any evidence that the rapid development of the obesity epidemic in emerging nations, and its unusual coexistence with malnutrition, may have evolutionary origins that make such populations especially vulnerable to the obesogenic conditions accompanying the nutrition transition. It is concluded that any selection of so-called ‘thrifty genes’ is likely to have affected most races due to the frequency and ubiquity of famines and seasonal food shortages in ancient populations. Although it remains a useful stimulus for research, the thrifty gene hypothesis remains a theoretical construct that so far lacks any concrete examples. There is currently little evidence that the ancestral genomes of native Asian or African populations carry particular risk alleles for obesity. Interestingly, however, there is evidence that a variant allele of the FTO gene that favors leanness may be less active in Asians or Africans. There is also some evidence that Caucasians may be less prone to developing type 2 diabetes mellitus than other races suggesting that there has been recent selection of protective alleles. In the near future, recently developed statistical methods for comparing genome-wide data across populations are likely to reveal or refute the presence of any thrifty genes and might indicate mechanisms of vulnerability.

Prenatal Origins of Undernutrition

Author(s): P. Christian

Undernutrition continues to be high in many regions of the developing world. Birthweight, a common proxy measure of intrauterine growth, is influenced by nutritional, environmental and lifestyle factors during pregnancy and, in turn, affects immediate survival and function, and is a determinant of later life risk of chronic diseases. Maternal pre-pregnancy weight and height are independently associated with birthweight and also modify the effects of pregnancy weight gain and interventions during pregnancy on birthweight and perinatal mortality. Other prenatal factors commonly known to impact birthweight include maternal age, parity, sex, and birth interval, whereas lifestyle factors such as physical activity and maternal stress, as well as environmental toxicants have variable influences. Tobacco and other substance use and infections, specifically ascending reproductive tract infections, malaria, and HIV, can cause intrauterine growth restriction (IUGR). Few studies have examined the contribution of prenatal factors including low birthweight to childhood wasting and stunting. Studies that have examined this, with adequate adjustment for confounders, have generally found odds ratios associated with low birthweight ranging between 2 and 5. Even fewer studies have examined birth length or maternal nutritional status as risk factors. More research is needed to determine the proportion of childhood undernutrition attributable to IUGR so that interventions can be targeted to the appropriate life stages.

Postnatal Origins of Undernutrition

Author(s): M.A. Prost

Obesity and nutrition-related chronic disorders are fast rising in developing countries. But undernutrition – stunting, underweight, wasting and micronutrient deficiencies – still affect millions of preschool children in both rural and urban settings increasing the risks of morbidity and mortality, impairing cognitive development, reducing productivity and increasing the risk of chronic diseases in later life. In addition undernutrition has a transgenerational effect. Here I review the evidence for a synergistic effect of inadequate nutrition (breastfeeding, complementary feeding), infection, and inappropriate mother–child interactions on growth and nutritional deficiencies. Underlying socioeconomic, environmental and genetic factors are also explored. Finally some perspectives on how urbanization and globalization may affect the prevalence and distribution of undernutrition are discussed. Fighting child undernutrition is still an urgent necessity and a moral imperative.

Malnutrition, Long-Term Health and the Effect of Nutritional Recovery

It is estimated that over 51 million people in Brazil live in slums, areas where a high prevalence of malnutrition is also found. In general, the population of ‘slum dwellers’ is growing at a faster rate than urban populations. This condition is associated with poor sanitation, unhealthy food habits, low birthweight, and stunting. Stunting is of particular concern as longitudinal and cross-sectional studies of stunted adolescents have shown a high susceptibility to gain central fat, lower fat oxidation, and lower resting and postprandial energy expenditure. In addition, higher blood pressure, higher plasma uric acid and impaired flow-mediated vascular dilation were all associated with a higher level of hypertension in low birthweight and stunted children. In particular, stunted boys and girls also showed lower insulin production by pancreatic B cells. All these factors are linked with a higher risk of chronic diseases later in life. Among stunted adults, alterations in plasma lipids, glucose and insulin have also been reported. However, adequate nutritional recovery with linear catch-up growth, after treatment in nutritional rehabilitation centers, can moderate the alterations in body composition, bone density and insulin production.

The Role of Epigenetics in Mediating Environmental Effects on Phenotype

Author(s): D.K. Morgan, E. Whitelaw

Epigenetics is being suggested as a possible interface between the genetic and environmental factors that together give rise to phenotype. In mice there exists a group of genes, known as metastable epialleles, which are sensitive to environmental influences, such as diet, and undergo molecular changes that, once established, remain for the life of the individual. These modifications are epigenetic and in some cases they survive across generations, that is, through meiosis. This is termed transgenerational epigenetic inheritance. These findings have led to the idea that similar processes might occur in humans. Although it is clear that the lifestyle of one generation can significantly influence the health of the next generation in humans, in the absence of supporting molecular data it is hard to justify the notion that this is the result of transgenerational epigenetic inheritance. What is required first is to ascertain whether genes of this type, that is genes that are sensitive to the epigenetic state, even exist in humans.

The coexistence of intrauterine and neonatal malnutrition and the development of obesity, type 2 diabetes and related comorbidities have been confirmed in a number of studies in humans and animal models. Data from studies in animals suggest that epigenetic changes as a result of altered methylation of the genomic DNA may be responsible for such metabolic patterning. Methionine, an essential amino acid, plays a critical role in the methyltranferases involved in the methylation by providing the one-carbon units via the methionine transmethylation cycle. Because of its interaction with a number of vitamins (B12, folate, pyridoxine), its regulation by hormones, i.e. insulin and glucagon, and by the changes in redox state, methionine metabolism is effected by nutrient and environmental influences and by altered physiological states. In the present review the impact of human pregnancy, dietary protein restriction and fatty liver disease on methionine metabolism is discussed. The role of methionine in metabolic programming in a commonly used model of intrauterine growth retardation and in propagation of fatty liver disease is briefly described.

Adiposity and Comorbidities: Favorable Impact of Caloric Restriction

Author(s): E. Ravussin, L.M. Redman

The focus here is on research involving long-term calorie restriction (CR) to prevent or delay the incidence of the metabolic syndrome with age. The current societal environment is marked by overabundant accessibility of food coupled with a strong trend to reduced physical activity, both leading to the development of a constellation of disorders including central obesity, insulin resistance, dyslipidemia and hypertension (metabolic syndrome). Prolonged CR has been shown to extend median and maximal lifespan in a variety of lower species (yeast, worms, fish, rats, and mice). Mechanisms of this lifespan extension by CR are not fully elucidated, but possibly involve alterations in energy metabolism, oxidative damage, insulin sensitivity, and functional changes in neuroendocrine systems. Ongoing studies of CR in humans now makes it possible to identify changes in ‘biomarkers of aging’ to unravel some of the mechanisms of its anti-aging phenomenon. Analyses from controlled human trials involving long-term CR will allow investigators to link observed alterations from body composition down to changes in molecular pathways and gene expression, with their possible effects on the metabolic syndrome and aging.

Obesity, Inflammation, and Macrophages

Author(s): V. Subramanian, A.W. Ferrante

The World Health Organization estimates that since 1980 the prevalence of obesity has increased more than threefold throughout much of the world, and this increase is not limited to developed nations. Indeed, the incidence of obesity is increasing most rapidly among rapidly industrializing countries raising the specter of a burgeoning epidemic in obesity-associated diseases, including diabetes, dyslipidemia, nonalcoholic fatty liver disease and atherosclerosis. Reducing the rates of obesity and its attendant complications will require both coordinated public health policy and a better understanding of the pathophysiology of obesity. Obesity is associated with low grade chronic inflammation, a common feature of many complications of obesity that appears to emanate in part from adipose tissue. In obese individuals and rodents adipose tissue macrophage accumulation is a critical component in the development of obesity-induced inflammation. The macrophages in adipose tissue are bone marrowderived and their number is strongly correlated with bodyweight, body mass index and total body fat. The recruited macrophages in adipose tissue express high levels of inflammatory factors that contribute to systemic inflammation and insulin resistance. Interventions aimed at either reducing macrophage numbers or decreasing their inflammatory characteristics improves insulin sensitivity and decreases inflammation. Macrophage accumulation and adipose tissue inflammation are dynamic processes under the control of multiple mechanisms. Investigating the role of macrophages in adipose tissue biology and the mechanisms involved in their recruitment and activation in obesity will provide useful insights for developing therapeutic approaches to treating obesity-induced complications.

Obesity, Hepatic Metabolism and Disease

Author(s): J.M. Edmison, S.C. Kalhan , A.J. McCullough

Nonalcoholic steatohepatitis (NASH), which is the most severe histological form of nonalcoholic fatty liver disease, is emerging as the most common clinically important form of liver disease in developed countries. Although its prevalence is 3% in the general population, this increases to 20–40% in obese patients. Since NASH is associated with obesity, its prevalence has been predicted to increase along with the growing epidemic of obesity and type 2 diabetes mellitus. The importance of this observation comes from the fact that NASH is a progressive fibrotic disease in which cirrhosis and liver-related death occur in 25 and 10% in these patients, respectively, over a 10-year period. This is of particular concern given the increasing recognition of NASH in the developing world. Treatment consists of treating obesity and its comorbidities: diabetes and hyperlipidemia. Nascent studies suggest that a number of pharmacological therapies may be effective, but all remain unproven at present. Histological and laboratory improvement occurs with a 10% decrease in bodyweight. Bariatric surgery is indicated in selected patients. A greater understanding of the pathophysiological progression of NASH in obese patients must be obtained in order to develop more focused and improved therapy.

Imperative of Preventive Measures Addressing the Life-Cycle

Author(s): C.S. Yajnik

The epidemiological characteristics of chronic non-communicable diseases (NCD) are fast changing. The prevalence has risen to unprecedented levels, and the young and the underprivileged are increasingly affected. The classic view of the etiology of NCD consists of a genetic susceptibility which is precipitated by aging and modern lifestyle. In a virtual absence of any methods to tackle genetic susceptibility, the preventive approach has so far been focused on the control of lifestyle factors in those at high risk (old, and those with positive family history and elevated risk factors). Such an approach might help high risk individuals, but is unlikely to curtail the burgeoning epidemic of obesity and diabetes. Recent research has suggested that susceptibility to NCD originates in early life through non-genetic mechanisms (fetal programming). Tackling these may offer an exciting opportunity to control the NCD epidemic by influencing the susceptibility in a more durable manner than only controlling the lifestyle factors in adult life. The imperative is to address the life cycle rather than concentrate on the end stages.

New Approaches to Optimizing Early Diets

Author(s): S. Polberger

Most extremely low birthweight (ELBW; <1,000 g) infants will survive if cared for at a tertiary neonatal intensive care unit, and should be given optimal nutrition for brain development. Human milk confers nutritional and non-nutritional advantages over infant formula, and is started during the first hours of life. In Sweden, most ELBW infants are fed individually with mother’s own milk (preferred) and banked milk, with supplementary parenteral nutrition. There is an enormous variation particularly in the fat and protein content of milk between mothers, during the day and the course of lactation. Infrared macronutrient analyses on 24-hour collections of mother’s milk are performed once a week allowing for optimal protein and energy intakes. All banked milk is analyzed, and the most protein-rich milk is given to a newborn ELBW infant. After 2 weeks, the milk may be fortified if the protein or energy intakes need to be further increased, and fortification is continued throughout the tube-feeding period. Parenteral nutrition is continued until the enteral intake constitutes 75–80% of the total volume intake. Protein markers, e.g. serum urea and transthyretin, are assessed, and growth is monitored by measurements of weight, crown–heel length and head circumference.

Prevention of Low Birthweight

Author(s): D.S. Alam

Globally an estimated 20 million infants are born with low birthweight (LBW), of those over 18 million are born in developing countries. These LBW infants are at a disproportionately higher risk of mortality, morbidity, poor growth, impaired psychomotor and cognitive development as immediate outcomes, and are also disadvantaged as adults due to their greater susceptibility to type 2 diabetes, hypertension and coronary heart disease. Maternal malnutrition prior to and during pregnancy manifested by low bodyweight, short stature, inadequate energy intake during pregnancy and coexisting micronutrient deficiency are considered major determinants in developing countries where the burden is too high. LBW is a multifactorial outcome and its prevention requires a lifecycle approach and interventions must be continued for several generations. So far, most interventions are targeted during pregnancy primarily due to the increased nutritional demand and aggravations of already existing inadequacy in most women. Several individually successful interventions during pregnancy include balanced protein energy supplementation, several single micronutrients or more recently a mix of multiple micronutrients. Nutrition education has been successful in increasing the dietary intake of pregnant women but has had no effect on LBW. The challenge is to identify a community-specific intervention package. Current evidence supports intervention during pregnancy with increased dietary intakes including promotions of foods rich in micronutrients and micronutrient supplementation, preferably with a multiple micronutrient mix. Simultaneously a culturally appropriate educational component is required to address misconceptions about diet during pregnancy and childbirth including support for healthy pregnancy with promotion of antenatal and perinatal care services. While further research is needed to identify more efficacious interventions, an urgent public health priority would be to select and implement an optimal mix of interventions to avert the immediate adverse consequences of LBW and to prevent the impending epidemic of type 2 diabetes, hypertension and coronary heart disease which are negatively associated with LBW.

Community-based approaches have been the mainstay of interventions to address the problem of child malnutrition in developing societies. Many programs have been in operation in several countries for decades and originated largely as social welfare, food security and poverty eradication programs. Increasingly conceptual frameworks to guide this activity have been developed as our understanding of the complex nature of the determinants of undernutrition improves. Alongside this evolution, is the accumulation of evidence on the types of interventions in the community that are effective, practical and sustainable. The changing environment is probably determining the altering scenario of child nutrition in developing societies, with rapid developmental transition and urbanization being responsible for the emerging problems of obesity and other metabolic disorders that are largely the result of the now well-recognized linkages between child undernutrition and early onset adult chronic diseases. This dramatic change is contributing to the double burden of malnutrition in developing countries. Community interventions hence need to be integrated and joined up to reduce both aspects of malnutrition in societies. The evidence that community-based nutrition interventions can have a positive impact on pregnancy outcomes and child undernutrition needs to be evaluated to enable programs to prioritize and incorporate the interventions that work in the community. Programs that are operational and successful also need to be evaluated and disseminated in order to enable countries to generate their own programs tailored to tackling the changing nutritional problems of the children in their society.